Flame tube shroud assembly for fuel injector nozzle

ABSTRACT

A flame tube assembly for a gas turbine engine includes a flame tube wall with two sets of circumferentially spaced apertures therethrough to provide communication between the inside of the flame tube and an external air passage. A fuel sprayer head is disposed with clearance in each of the first set of apertures and a shroud surrounds each fuel sprayer head. Each shroud has two hollow limbs extending on opposite sides of the fuel sprayer head and a downstream end portion which interconnects downstream ends of the limbs with adjacent apertures of the second set. The limbs and associated downstream end portion of each shroud have openings therein directed towards the fuel sprayer head. Each limb has an upstream opening so that air from the passage is directed into the hood to enter the flame tube via the first set of openings and around each fuel sprayer head.

United States Patent Carr et al.

FLAME TUBE SHROUD ASSEMBLY FOR FUEL INJECTOR NOZZLE [75] Inventors: Eric Carr, Blackburn; Kenneth McClave, Nelson, both of England [73] Assignee: Lucas Aerospace Limited,

Birmingham, England [22] Filed: July 2, 1974 [21] Appl. No.: 485,250

[30] Foreign Application Priority Data July 5, 1973 United Kingdom 32091/73 [52] US. Cl. 60/39.74 R; 60/3966 [51] Int. Cl. F02G 3/00 [58] Field of Search 60/3974 R, 39.65, 39.66,

[56] References Cited UNITED STATES PATENTS 2,851,859 9/1958 Foure 60/3965 2,907,171 10/1959 Lysholm 60/3965 2,926,495 3/1960 Benson et al. 60/3974 R 3,030,774 4/1962 Henning et al. 60/3967 X 3,088,279 5/1963 Diedrich 60/3965 X Primary Examiner-C. J. Husar Assistant Examiner-Thomas 1. Ross ABSTRACT A flame tube assembly for a gas turbine engine includes a flame tube wall with two sets of circumferentially spaced apertures therethrough to provide communication between the inside of the flame tube and an external air passage. A fuel sprayer head is disposed with clearance in each of the first set of apertures and a shroud surrounds each fuel sprayer head. Each shroud has two hollow limbs extending on opposite sides of the fuel sprayer head and a downstream end portion which interconnects downstream ends of the limbs with adjacent apertures of the second set. The limbs and associated downstream end portion of each shroud have openingstherein directed towards the fuel sprayer head. Each limb has an upstream opening so that air from the passage is directed into the hood to enter the flame tube via the first set of openings and around each fuel sprayer head.

2 Claims, 2 Drawing Figures U.S. Patent Nov. 25, 1975 FLAME TUBE SHROUD ASSEMBLY FOR FUEL INJECTOR NOZZLE This invention relates to a flame tube assembly for a gas turbine engine.

According to the present invention, there is provided a flame tube assembly for a gas turbine engine, said assembly including a flame tube wall, a fuel sprayer head mounted in an aperture in the flame tube wall, a clearance between the sprayer head and the wall around the aperture for flow of air, in use, from an air passage outside the flame tube wall to the interior of the flame tube, and a shroud mounted on the exterior of the flame tube wall and disposed around the said clearance, said shroud having at least one air inlet which is disposed upstream of the clearance relative to the direction of flow of air in the air passage, in use.

Preferably, the shroud comprises two hollow limbs which extends on either side of the fuel sprayer head, each limb having an exit opening on an inner side thereof which is presented to the fuel sprayer head.

Most advantageously, the shroud has a downstream end portion which opens into at least one further aperture in the flame tube wall.

Conveniently, the said downstream end portion interconnects the two hollow limbs at the downstream ends thereof, the upstream ends of the two hollow limbs each having said air inlet therein.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic perspective view of part of the flame tube assembly for a gas turbine engine, according to the present invention, and

FIG. 2 is a section on the line 2--2 of FIG. 1.

Referring to the drawing, the flame tube assembly is of the annular type and includes an annular, composite flame tube wall having'a plurality of first apertures 11 therein (only one shown) and a plurality of further apertures 12 therein. Each set of first apertures 11 and further apertures 12 are spaced apart circumferentially of the flame tube wall 10. As can be seen from FIG. 2, the apertures 11 have their axes radially disposed relative to a longitudinal axis of the flame tube assembly whilst the apertures 12 have their axes disposed substantially parallel to the longitudinal axis of the flame tube assembly. Mounted in each aperture 11 is a fuel sprayer head 13 of known type (see FIG. 2). The sizing of the apertures 11 and fuel sprayer head 13 is such that a clearance 14 is defined between the fuel sprayer head 13 and the wall 10 around aperture 11, the clearance 14 extending around the fuel sprayer head 13. As is conventional in flame tube assemblies, a combustion zone 15 is defined internally of the annular flame tube flow of air in passage 16. Each shroud 17 also includes a downstream end portion 20 which interconnects the limbs 18 and 19. As can be seen best in FIG. 2, the downstream end portion 20 of each shroud 17 communicates with several of the apertures 12 in the wall 10. Each of the limbs 18 and 19 is hollow and is provided with a respective air inlet 21 and 22 at its upstream end relative to the direction of air flow in passage 16. Furthermore, each limb 18 and 19 is provided with a respective exit opening 23 and 24 in an inner side thereof which is presented to the respective fuel sprayer head 13. Similarly, the downstream end portion 20 of each shroud 17 has an upstream opening 25 therein which is presented to the fuel sprayer head 13 and which interconnects openings 23 and 24. Each shroud l7 surrounds the clearance 14 between each fuel sprayer head 13 and the wall 10 around the respective first aperture 11.

In use, each fuel sprayer head 13 serves to supply fuel into the combustion zone 15 in known manner. Air is also introduced into the combustion Zone 15 inter alia through apertures 12. In order to pass through the apertures 11 and those apertures 12 which are covered by downstream end portion 20 of hood 17, air must first pass into hood l7 and it does so by entering inlets 21 and 22 at the upstream end of hood 17. A certain amount of air passes between limbs 18 and 19 to enter the upstream end of each respective first aperture 11 beneath a cranked portion 26 of the respective fuel sprayer head 13. Some of the air entering inlets 21 and 22 in limbs 18 and 19, respectively, passes into the associated first aperture 11 via openings 23 and 24 whilst the remaining air passes into the downstream end portion 20 of the shroud 17 and from thence into the flame tube through apertures 12.

The provision of the shroud 17 prevents so-called torching or escape of the flame from the combustion zone 15 into the air passage 16. Furthermore, the provision of the hood 17 further assists in cooling of the associated fuel sprayer head 13.

We claim:

1. A flame tube assembly for a gas turbine engine, said assembly including a flame tube wall, a fuel sprayer head mounted in an aperture in said flame tube wall, a clearance between said fuel sprayer head and the wall around the aperture for flow of air from an air passage outside said flame tube wall to the interior of said flame tube, and a shroud mounted on the exterior of said flame tube wall and disposed around said clearance, said shroud comprising two hollow limbs which extend on either side of said fuel sprayer head and a downstream end portion which interconnects said two hollow limbs at downstream ends thereof, each said limb having an air inlet at the upstream end thereof which is disposed upstream of said clearance relative to the direction of flow of air in the air passage, and also having an exit opening on an inner side thereof which is presented to said fuel sprayer head.

2. The flame tube assembly according to claim 1, wherein said downstream end portion of said shroud opens into at least one further aperture in said flame 

1. A flame tube assembly for a gas turbine engine, said assembly including a flame tube wall, a fuel sprayer head mounted in an aperture in said flame tube wall, a clearance between said fuel sprayer head and the wall around the aperture for flow of air from an air passage outside said flame tube wall to the interior of said flame tube, and a shroud mounted on the exterior of said flame tube wall and disposed around said clearance, said shroud comprising two hollow limbs which extend on either side of said fuel sprayer head and a downstream end portion which interconnects said two hollow limbs at downstream ends thereof, each said limb having an air inlet at the upstream end thereof which is disposed upstream of said clearance relative to the direction of flow of air in the air passage, and also having an exit opening on an inner side thereof which is presented to said fuel sprayer head.
 2. The flame tube assembly according to claim 1, wherein said downstream end portion of said shroud opens into at least one further aperture in said flame tube wall. 